Directional window cutter for whipstocks



J. s; BECK 4 DIRECTIONAL WINDOW uTTER FoR wmPsTocxs Filed June 1o, 1957 April 14, `1959 2 Sheets-Sheet 1 IN VEN TOR.

ATTORNEY F IG. I4,

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April 14, 1959 J. s. BECK A DIRECTIONAL wINnow CUTTER FCR wHIFsTocxs Filed June 1o, 1957 2 sheets-shea 2 IN V EN TOR.

JUL/Us s. BEC/f uamwmmusnw nIIVI;Illllrllllflllllllillllllllfllfllllllllllllflllililllllllil il!!! I llllllllllll Il lallffllr4!lilllndlflllllllirlllfII Y u .li W 6 H ATTORNEY nite States Patent DIRECTIONAL WINDOW CUTTER FOR WHIPSTOCKS Julius S. Beck, Long Beach, Calif., assgnor to J. E. Hill, Fort Worth, Tex.

Application June 10, 1957, Serial No. 664,602

7 Claims. (Cl. Z55-1.6)

This invention relates to the rotary method of drilling wells and has reference to a whipstock and mill for cutting a side opening or window in casing in a well bore. This application is a continuation in part of my copending application, Serial No. 373,116, filed August 10, 1953, now Patent No. 2,807,440, issued Sept. 24, 1957. Generally, the invention is directed to improved apparatus for sidetracking an obstruction in a well, for diversional drilling, and for other whipstock operations.

Heretofore, side openings were made in Well casings by various methods, such as shooting explosives, the use of various types of successive graduated mills, grinding abrasives against the casing wall, and ripping the casing with special tools for that purpose; however, such methods were objectionable because they left ragged edges and irregular openings in the casing. Sometimes the resulting openings were too small for the intended purpose, and in some instances the openings extended more than one-half the diameter of the casing. In many instances the casing was weakened and parted causing diiculties in continuation of drilling. The ragged edges around the casing opening in prior methods severely scored the drill stem and sometimes cut through the same with the result that a diflicult fishing job followed.

An object of the invention is to cut a maximum size Window or opening in the side of a casing in a well bore; that is, to make the size of the opening in the casing equal to the inside diameter of the casing in a single operation.

Another object is to provide means for accurately controlling the angle of declination with respect to the axis of the well bore.

A particular object of the invention is to provide a multiple milling cutter assembly which will not leave an elliptical casing sliver such as formed when using a single rotary hollow mill.

Another object is to provide an inclination control mandrel which may be adjusted to prevent the first mill of a multiple mill assembly from contacting and marring the whipstock and thus prevent unnecessary wear on the mills.

A further object is to provide means whereby the milling cutter is prevented from penetrating the casing too abruptly; which abrupt penetration would result in a dog leg or opening which would be dicult to enter during subsequent drilling operations.

Other objects will become apparent from the following description which has reference to the accompanying drawings, wherein:

Figure 1 is a vertical section of a well casing and shows the present invention positioned to begin its cutting operation.

Figure 2 is a broken elevation of a well casing in an earth formation and showing the present invention after the same has cut a casing opening.

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Figure 3 is a vertical sectional view of a casing and showing the casing opening formed by the present apparatus.

Figure 4 is a broken section and elevation of the present multiple milling cutter assembly.

Figure 5 is an enlarged vertical section of the large milling cutter and the mandrel on which it is mounted.,

Figure 6 is a vertical sectional view of the casing and showing the upper portion of the whipstock in section and illustrating the hinged adjustment of the mandrel bearing.

Figure 7 is a vertical sectional view showing the relative positions of the two milling cutters after the casing has been partly cut. p

Figure 8 is a sectional view similar to Figure 7, and showing a further step in the cutting operation.

Figure 9 is a transverse section taken on line 9--9 of Figure 6. 5

Figure l0 is an enlarged transverse section taken on line 10--10 of Figure 6. v

Figure 11 is an enlarged transverse section taken on line 11-11 of Figure 6.

Figure 12 is an enlarged transverse section taken on the larger milling cutter partially through the casing` and wherein part of the weight of the drill pipe is supported thereon.

As shown in the drawings, particularly Figure l, the

primary components of the invention are an anchor 15, a whipstock 16 supported on and above the anchor, a

dual milling cutter assembly 17, and a bearing support generally indicated at 18. The anchor is comprised of a hollow cylindrical body 19 having a shoulder 20 there-- around for supporting split collet type slips 21, the latter being secured to the body 19 by means of screws 22 through the circular lower portion of the body. A-

round nose plug 23 is threaded in the lower end` of the slip body 19, and which plug has an axial lluidA circulating port 24 therethrough. In addition to the external teeth 25 on the slips 21, the slips are providedwith internal teeth 26 arranged to engage the conical surface of a wedge 27 threadedly engaged in the lower end of the whipstock 16. Both the wedge 27 and whip- There is a stock 16 have axial passages 28 and 29. depending wedge extension 30 integral with the lower end of the wedge 27 for slidably engaging the anchor body 19 and supporting anchor 15 when the present apparatus is being placed in operating position. The last referred to engagement is accomplished by means of a screw 31 extending through the wall of the anchor body 19 where it engages the upper surface of a shoulder 32 on the lower end of the wedge extension 30. The shoulder 32 is formed by reducing the outside diameter of the extension 30 between the ends thereof, and the length of which is of reduced diameter 33 to provide limited longitudinal movement between the anchor 15 and the whipstock 16.

The whipstock 16 includes the usual inclined guiding surface 34, arcuate in cross section, and near the top` 16, whereas the adjacent sides 37 of the support project perpendicularly Ato provide a cradle for a mandrel bearing 38 received therebetween. The bearing 38 is hingedly supported by plain end set screws 39 in the support'sides 37, the axisl of which is perpendicular to the "axis of thebearinglbore'i. 'As shown in'Figure ll, the surface 41 of the bearing 38 between the inner corners of the sides 37 is preferably ilat and spaced from the opposing at surface 42 of the support 35 to permit limited hinged movement of the bearing 3S. As shown in Figures land 6, the hinge screws 39 are near the top of the support 35 and bearing 38, and are inwardly positioned with respect to the axis of the bearing bore 40. The angular position of the bearing 38 is determined and fixed by means of an angle control set'screw 43-threade'd in the-upper portion of the support-SS-and'in engagement with the flat surface 41 of the bearing. The axis of the angle control set screw 43 is perpendicular'to, but below the axis of the hinge screws 39. A depending stop 44, for contact with the surface of the support 35, may be provided at the lower end of the llat bearing surface 41 for further limiting the hinged movement of the bearing 38. A hole 4S is provided in the whipstock 16 for access to the outer end of the angle control set screw 43.

The dual mill cutter assembly 17 includes a tubular mandrel 46 rotatably and slidably mounted in and extending through the bore of the bear-ing 38. A conical pilot milling cutter 47 is secured to the lower end of the mandrel 46, which cutter has circulation ports 4S between the cutter blades 49 for communication with the axial opening through the mandrel. The upper portion of the dual milling cutter assembly 17 is comprised of an upper sub 50 for connection with the lower end of ya drill pipe 51, a connecting sub 52, a tubular receiver S3, an adapter sub 54, a cylindrical mill support and a primary cutting mill 56. As will be apparent from Figure 6 of the drawing the diameter of the primary cutter 56 is substantially equal to the internal diameter of the casing 71.

The passage 57 through the upper sub 50 is of somewhat reduced diameter so as to provide sucient material for internal threads 58 in the lower end thereof, which threads are yadapted to engage external threads 59 on the upper end of the mandrel 46. As shown in Figure 5, the upper end of the mandrel 46 is of reduced diameter so as to provide a shoulder 60 for supporting a bearing sleeve 61 thereon. The bearing sleeve 61 is a sliding t inthe adapter sub 54, the 'tubular receiver 53, and the Vconnecting sub 52. The bearing sleeve 61 is rotatably mounted on the upper end of the mandrel 46 where the latter is provided vwith a circular groove 62 on its outer surface for receiving the round end of a retaining screw 63 threadedly engaged in the said sleeve. Ring seals 64 may be provided around the sleeve 61 to prevent entry of drilling fluids around the mandrel 46.

The lower end of the cylindrical mill support 55 is counterbored to receive a flanged bearing 65 for slidably and rotatably receiving the mandrel 46. Similarly, the axial center of the mill or primary cutter 56 is provided with an openingfor the same purpose. It will be Inoted'that the blades '66 of the mill 56 extend inwardly to the diameter of the mandrel 46, and that the blades 49 on the lower mill extend outwardly beyond the mandrel diameter. Thus, the two mills, when in operation, act upon and cut an entire circular area as will become apparent from the description of operation to follow.

A threaded shear pin 67 is positioned through the side of the adaptersub 54 and into the mandrel 46 near the top `thereof for initially maintaining the pilot and primary.millingcutters 47 and 56 in extended spaced relation whereby downward and lateral sliding movement is imparted to the bearing support 18 mounted on the upper inclined surface of the whipstock 16. The sliding movement last referred to is accomplished by means of the connection-between the whipstock 16 and bearing support 18, which connection is comprised of an inwardly shouldered vertical slot 68, a holding plate 69 slidably mounted in the slot, and bolts 70 through the plate and threaded in the bearing support.

Operation In operation, the angle control screw 43 is rst adjusted to determine the angle of declination, after which the described apparatus is lowered in the well casing 71 by means of the drill pipe 51 until the nose 23 of the anchor 15 contacts the obstruction 72 in the casing. In some operations, it is a pinched casing to be sidetracked, and in which case the nose 23 contacts the pinched casing portion. In other operations, as in directional drilling, a plug (not shown) may be set in the casing for seating the anchor 15.

When the apparatus is suspended, as during the lowering operation, the bearing support 18 is in a raised position on the upper end of the whipstoek 16, and the slips 21 are retracted by reason of the suspended position of the anchor 15. When the anchor nose 23 makes contact, as above referred to, continued downward movement of the drill pipe causes the cylindrical wedge 27 on the lower endof the whipstock 16 to expand the slips 21 and grip the inner surface of the casing 71. The last referred to operation is carried out by means of the external teeth 25 on the slips 21 and at the same time the internal teeth26 grip the wedge 27. Thus, the whipstock 16 is secured against rotation in the casing 71. Continued downward movement of the drill pipe 51 brings the lower cutter 47 in contact with the inner surface of the casing 71, and after which the shear pin 67, connecting the adapter sub 54 with the mandrel 46, is sheared. The lower cutter 47 in contact with the casing 71 secures the mandrel 46 against rotation during the immediately following stage of the operation. Rotation of the drill pipe 51, and downward movement thereof, causes the upper mill 56 to begin the window cutting operation in the casing. As the upper mill 56 moves downwardly, the upper end of the mandrel 46 is slidably received through the upper or primary cutter 56, the cutter bearing 65, adapter sub 54, tubular receiver 53, and ultimately the threads 59 in the upper end of the mandrel engage the threads 58 in the lower end of the upper sub 50. After the threaded engagement takes place, the lower mill or pilot cutter 47 begins its cutting operation. Continued downward cutting causes the upper mill or primary cutter 56 to cut away the bearing support 35 and bearing 38; however, by this time the angle of the cut has been started and additional guiding of the cut is by reason of the contact of the primary mill 56 on the inclined surface 34 of the whipstock 16. The resulting cut is an elliptical opening '73 or window as shown in Figure 3, and after which the drilling operation is continued into the earth formation 74, as shown in Figure 2. Smaller casing (not shown) for the sidetrack bore 75 is then lowered through the previously described casing 71 and set in the usual manner.

The invention is not limited to the exemplary construction herein shown, but may be varied within the scope of the accompanying claims.

What is claimed is:

1. Apparatus for cutting a side opening in a casing in a well bore, comprising an anchor including means for securing the same to the inner surface of the casing, a bearing supported and secured by said anchor at the upper end thereof, the axis of said bearing being angularly positioned with respect to the axis of the well bore, a mandrel rotatably and slidably mounted in and extending through said bearing, a primary mill cutter, means for securing the primary mill cutter to the lower end of a rotary drill pipe above said bearing, a pilot milling cutter secured to the lower end of said mandrel below said bearing, said primary cutter including an axial opening therethrough slidably and rotatably receiving said mandrel, and means engaging the pilot cutter with said primary cutter to rotate therewith when said mandrel is substantially fully received in the primary cutter.

2. Apparatus as set forth in claim 1, wherein a whipstock is mounted on said anchor and said bearing is mounted on the upper inclined surface of said whipstock.

3. Apparatus as set forth in claim 2, wherein the bearing is mounted for slidable movement along the inclined surface of said whipstock.

4. Apparatus for cutting a side opening in a casing in a well bore as defined in claim 1, the construction wherein said bearing is hingedly supported above said anchor, the hinged axis being perpendicular to the axial bore of the bearing.

5. Apparatus for cutting a side opening in a casing in a well bore as dened in claim 4, and including a screw carried by said anchor, one end of said set screw being in contact with said bearing, the axis of said screw being offset with respect to the hinged axis of the bearmg.

6. A cutting apparatus as set forth in claim 1, wherein the diameter of the primary mill cutter is of substantially the same diameter as the diameter of the casing, and the diameter of the pilot cutter is of less diameter than the diameter of the primary cutter but of greater diameter than the axial opening in the primary cutter, and the combined cutting surfaces of the primary and pilot cutters being such that a complete side opening is cut in the casing by the two cutters combined.

7. A cutting apparatus as set forth in claim 1, wherein the said bearing is formed of readily drillable material.

References Cited in the le of this patent UNITED STATES PATENTS 1,636,032 Abbott July 19, 1927 2,105,722 Barrett et a1. Ian. 18, 1938 2,586,939 Grable Feb. 26, 1952 

